Effect of $\hbox{F}_{2}$ Postmetallization Annealing on the Electrical and Reliability Characteristics of HfSiO Gate Dielectric

The effects of fluorine (F
₂
) annealing on the electrical and reliability characteristics of HfSiO MOSFETs were investigated. Compared with a control sample annealed in conventional forming gas (H
₂
/N
₂
=4%/96%), additional annealing in a fluorine ambient (F
₂
/Ar=0.3%/99.7%) at 400 degC for 20 min improved the electrical characteristics such as lower interface trap density and higher transconductance. In addition, MOSFET samples annealed in a F
₂
ambient exhibited less degradation under hot-carrier stress and positive bias temperature stress. These improvements can be explained by fluorine incorporation at the high-k/Si interface, which was confirmed by an X-ray photoelectron spectroscopy analysis